1. Field of the Invention
The present invention relates to a device and method for regulating sensitivity of input devices, and especially to a method for regulating sensitivity of an electrical touch pad and the electrical touch pad using the same.
2. Description of Related Art
Touch pads are one type of popular input devices. The touch pads are often incorporated in electrical devices, such as portable computers, and functioned as a mouse. Touch pads have an operating surface that is physically touched by users. One of the most common types of the touch pads can be called an electrical touch pad comprising a resistive touch pad and a capacitive touch pad. The electrical touch pad generally includes a sensor for sensing inputs of the user, thus generating analog signals according to the inputs.
When the sensor of the electrical touch pad is activated, change in electrical current can be detected and measured by the electrical touch pad, thereby the inputs are processed. For example, the sensor of the capacitive touch pad typically includes a substrate which supports a first and a second interleaved, closely spaced, non-overlapping arrays of conductive plates. An insulating layer overlies the first and the second arrays. When an outer surface of the insulating layer is touched, the capacitances of at least one of the columns of plates of the first array and at least one of the rows of plates of the second array underlying the insulating layer at a location being touched exhibits a change with respect to ambient ground. Based upon the measured capacitance of each column of the first array and each row of the second array, signals representing the coordinates of the location being touched can be generated by a processor electrically connected to the sensor. These signals may be used, for example, to control a position of a cursor on a display screen of a portable computer or to make a select operation. However, changes in ambient humidity may result in erratic behavior of the electrical touch pad.
Therefore, a heretofore unaddressed need exists in the industry to overcome the aforementioned deficiencies and inadequacies.